The invention relates to a telescopic rail. A known telescopic rail from practice is, for instance, supplied by the firm Jonathan, Fullerton, USA.
The known telescopic rail comprises a first section having a substantially C-shaped cross section whose back is provided with a guide rail which, with the interposition of a ball cage, is bearing-mounted in a second section likewise having a substantially C-shaped cross section.
The first section can be slid relative to the second section in the longitudinal direction, between a retracted position and an extended position. Provided in the back of the first section is an opening, adjacent the end which trails in the extending direction. By means of an axis that extends at right angles to the back of the first section, a blocking means is provided, comprising lips extending through the opening, which blocking means is moved into a blocking position under the influence of gravity. Adjacent the end of the second section which end leads in extending direction, there is provided at least one projection which lies in the path of travel of the blocking means when they are in the blocking position. The blocking means can pass the blocking projection by moving slightly upwards. Thus, the blocking means can be retained behind the blocking projection, i.e. between the blocking projection and the end of the second section that leads in extended direction. When the first section is being retracted relative to the second section, the blocking means should be pulled up slightly, causing the blocking lip to be moved from the path of the blocking projection, after which it can be passed. The desired lifting movement can be manually effected, yet in this known telescopic rail, this is brought about by a third section of a likewise C-shaped cross section, which third section is movable within the C-shaped first section and lifts the blocking means from the blocking position when the third section is being slid into the first section, in the direction of the retracted position.
This known telescopic rail has as a drawback that the blocking means are relatively costly in manufacturing, while the positioning thereof is moreover laborious and costly. In addition, these blocking means have the drawback of producing relatively much noise, in particular during movement into and out of the blocking position. Further, these blocking means require relatively much building-in space, in particular building-in length. Also, these blocking means have the drawback of being located adjacent the end of the first section which trails in extending direction, as a consequence of which this section should be relatively long. After all, at least a portion thereof should, in the extended position, extend behind the ball cage. A further major drawback of this known telescopic rail is that it can only be used with the backs of the sections in a vertical plane, as the operation of the blocking means is based upon gravity.